Jim Nelson who was the Editor in Chief of GQ magazine for the past 15 years decided to leave. Condé Nast announced that it was replacing its editor in chief. Earlier this year, GQ won two National Magazine Awards and a Pulitzer Prize. He will be replaced by Will Welch, GQ’s creative director and the editor of its quarterly fashion-focused spinoff, GQ Style.

“I’ve been at GQ for 21 years and in this job for more than 15 — a good, long, productive run, not to mention a ton of fun — and I’ve gotten to work with some of the most talented writers, editors, photographers, designers and creative minds in the business,” Nelson said in a statement. “So I leave feeling proud and confident in the excellence of the work we’ve done together, but more than that, grateful.”

Before joining GQ, Nelson worked as a field producer for CNN, an assistant for television writers in Los Angeles and an editor at Harper’s Magazine. He followed Art Cooper as GQ’s top editor in 2003.

Nelson kept an emphasis on long feature stories — by writers like Andrew Corsello, Chris Heath, George Saunders, Amy Wallace and Taffy Brodesser-Akner (who is now working at The New York Times) — while doing away with Mr. Cooper’s boozy, Rat Pack sensibility.

Brodesser-Akner described Nelson as a champion of writers. “He was in awe of good writing. It mattered more than anything. I never experienced that from an editor in chief before that,” she said.

When the 2018 Pulitzer Prizes were announced in April, GQ became one of the few magazines to win the award. The winning article, by Rachel Kaadzi Ghansah, was the magazine’s profile of the white supremacist and mass murderer Dylann Roof.

The replacement of Nelson, 55, with Welch, 37, is part of a generational shift at Condé Nast.Nelson’s departure comes amid financial woes at Condé Nast, which lost more than 20 percent of its ad pages last year, according to the research firm Kantar Media. As the industry has shrunk, GQ has been hit with significant layoffs, and Condé Nast announced last year that it would cut the magazine’s print frequency to 11 annual issues from 12.